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AWS APIs library for Erlang
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src/erlcloud_retry.erl
%% -*- mode: erlang;erlang-indent-level: 4;indent-tabs-mode: nil -*-
%% @author Ransom Richardson <ransom@ransomr.net>
%% @doc
%%
%% Implementation of retry logic for AWS requests
%%
%% Currently only used for S3, but will be extended to other services in the furture.
%%
%% The pluggable retry function provides a way to customize the retry behavior, as well
%% as log and customize errors that are generated by erlcloud.
%%
%% @end
-module(erlcloud_retry).
-include("erlcloud.hrl").
-include("erlcloud_aws.hrl").
%% Helpers
-export([backoff/1,
no_retry/1,
default_retry/1, default_retry/2
]).
-export_type([should_retry/0, retry_fun/0]).
-type should_retry() :: {retry | error, #aws_request{}}.
-type retry_fun() :: fun((#aws_request{}) -> should_retry()).
%% Internal impl api
-export([request/3]).
%% Error returns maintained for backwards compatibility
-spec no_retry(#aws_request{}) -> should_retry().
no_retry(Request) ->
{error, Request}.
%% Sleep after an attempt
-spec backoff(pos_integer()) -> ok.
backoff(1) -> ok;
backoff(Attempt) ->
timer:sleep(erlcloud_util:rand_uniform((1 bsl (Attempt - 1)) * 100)).
%% Currently matches DynamoDB retry
%% It's likely this is too many retries for other services
-define(NUM_ATTEMPTS, 10).
-spec default_retry(#aws_request{}) -> should_retry().
default_retry(Request) ->
default_retry(Request, ?NUM_ATTEMPTS).
-spec default_retry(#aws_request{}, integer()) -> should_retry().
default_retry(#aws_request{attempt = Attempt} = Request, MaxAttempts)
when Attempt >= MaxAttempts ->
{error, Request};
default_retry(#aws_request{should_retry = false} = Request, _) ->
{error, Request};
default_retry(#aws_request{attempt = Attempt} = Request, _) ->
backoff(Attempt),
{retry, Request}.
request(Config, #aws_request{attempt = 0} = Request, ResultFun) ->
request_and_retry(Config, ResultFun, {retry, Request}).
request_and_retry(_, _, {error, Request}) ->
Request;
request_and_retry(Config, ResultFun, {retry, Request}) ->
#aws_request{
attempt = Attempt,
uri = URI,
method = Method,
request_headers = Headers,
request_body = Body
} = Request,
Request2 = Request#aws_request{attempt = Attempt + 1},
RetryFun = Config#aws_config.retry,
Rsp = erlcloud_httpc:request(URI, Method, Headers, Body,
erlcloud_aws:get_timeout(Config), Config),
case Rsp of
{ok, {{Status, StatusLine}, ResponseHeaders, ResponseBody}} ->
Request3 = Request2#aws_request{
response_type = if Status >= 200, Status < 300 -> ok; true -> error end,
error_type = aws,
response_status = Status,
response_status_line = StatusLine,
response_headers = ResponseHeaders,
response_body = ResponseBody},
Request4 = ResultFun(Request3),
case Request4#aws_request.response_type of
ok ->
Request4;
error ->
request_and_retry(Config, ResultFun, RetryFun(Request4))
end;
{error, Reason} ->
Request4 = Request2#aws_request{
response_type = error,
error_type = httpc,
httpc_error_reason = Reason},
request_and_retry(Config, ResultFun, RetryFun(Request4))
end.